Barber’s pole monitoring and decision-making

Barber’s Pole worm (Haemonchus contortus) season is ahead of us… somewhere!

This sub tropically-adapted parasite prefers the warmer conditions of summer. It sucks blood from the stomach lining of naive sheep, and big burdens can remove enough blood to kill lambs and (less often) adult sheep.

It can ‘seem’ to strike without warning; mostly in late summer and autumn, though we do see the odd case prior to Christmas from time to time. Most outbreaks occur after a spell of hot, dry weather followed by some moisture. The textbooks say 25mm of rain, but a few heavy dews can be enough to spark it up.

With the right environmental conditions, and in the absence of effective management/control, ‘outbreak’ situations occur where larval numbers on pasture rise rapidly. Their ingestion by grazing sheep results in the sudden appearance of ill-thrift, lethargy and deaths.

One of the problems with Barber’s Pole is in predicting the seasonal onset of challenge. A study in the Manawatu found no correlation between farms for the timing and severity of Barber’s Pole challenge. Just because one farm had high levels, did not mean a nearby farm would be similar. And even on the same farm, the relationship between Barbers Pole levels in the ewes and lambs was weak.

Anyone who’s been caught by a decent Barber’s Pole outbreak can be forgiven for thinking it’s not worth taking the risk of leaving stock unprotected. But is it necessary every year? And what are the sustainability costs of doing this?

Could you better assess the situation on your place each year?

  • An early faecal egg count (FEC) of lambs, even while still on mum, can be a guide; the egg counts of unweaned lambs can vary enormously, and very high FECs could point to Barbers Pole being present.
  • Consider investing $70.00 in a larval culture – we send a mixed faecal sample to the laboratory to hatch and grow out the eggs. The larvae are examined under a microscope and we get a breakdown of the species present.
  • Often pre-Christmas there will be no or very few Barbers Pole in these samples, but if you find there are, it can be a cue to early action.
  • Watch this space – in the future we will have a faster DNA based test to determine which worm species are present in faecal samples. When this is available it will really help in rapid decision-making around Barbers Pole Worm.
  • If you are handling lambs, look for paleness of the eye membranes. Normal eye membranes (the pink tissue under the lower lid is easiest to look at) are a salmon pink colour. Gums are hard to assess. They often look pale, even in healthy lambs.

Other protective measures

  • Keep drench intervals tidy on lambs grazing contaminated pasture - 28 days, don’t stretch them out.
  • Monitor ewes, 2ths and lambs separately. It may be necessary to treat 2ths for Barbers Pole without all MA ewes requiring a treatment.
  • Faecal egg counts of lambs just prior to when they require their next drench can be enlightening. If high counts are developing quickly, it could be due to Barbers Pole worm.

Specific drench options in our clinics for Barbers Pole include Exodus®, Cydectin®, Pentamox®, and for those containing multiple actives: Trimox® and Genesis® Ultra.  Please ask if you need advice on which product is best for your flock.

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